[tcat][ble] fixes to connection state mgmt and Disconnect cmd (#10619)

- Fixes to connection state management and handling of Disconnect
  command TLV
  - specifically, this now ensures that TCAT remains on (started)
    after a commissioner disconnects. Earlier, there was the problem
    that the 2nd commissioner couldn't connect anymore.
  - specifically, in ble_secure.cpp the check for if
    (mTcatAgent.IsEnabled()) is removed, since the err =
    mTcatAgent.Connected(mTls) will already check this and raise an
    error if not enabled. If not enabled, the Device is in a wrong
    state to handle TCAT Commissioner commands so now it closes the
    connection right away. That's better than to leave the
    Commissioner in limbo on the TLS connection. The Commissioner can
    now retry again and all will be well again.
- timeout of at most 10 seconds on UDP write operation in simulation
  mode (if longer, the TCAT device isn't reachable and the
  Commissioner now shows the error to the user.) Earlier, it got stuck
  forever.
- Corrects some copy/paste errors in API definitions in comments; adds
  comments where needed to explain.
  - adds whitespace at some places to align format with rest of code
- improved some of the --debug output for the UDP simulation mode of
  the TCAT Commissioner.

tools/tcat_ble_client/bbtc.py

@@ -102,9 +102,6 @@ async def main():
     while True:
         user_input = await loop.run_in_executor(None, lambda: input('> '))
         if user_input.lower() == 'exit':
-            print('Disconnecting...')
-            if ble_sstream is not None:
-                await ble_sstream.close()
             break
         try:
             result: CommandResult = await cli.evaluate_input(user_input)
@@ -113,6 +110,10 @@ async def main():
         except Exception as e:
             logger.error(e)
 
+    print('Disconnecting...')
+    if ble_sstream is not None:
+        await ble_sstream.close()
+
 
 async def get_device_by_args(args):
     device = None

tools/tcat_ble_client/ble/ble_stream_secure.py

@@ -140,6 +140,7 @@ class BleStreamSecure:
 
     async def close(self):
         if self.ssl_object.session is not None:
+            logger.debug('sending Disconnect command TLV')
             data = TLV(TcatTLVType.DISCONNECT.value, bytes()).to_bytes()
             await self.send(data)
 

tools/tcat_ble_client/ble/udp_stream.py

@@ -28,25 +28,31 @@
 
 import logging
 import socket
+import select
 
 logger = logging.getLogger(__name__)
 
 
 class UdpStream:
     BASE_PORT = 10000
+    MAX_SERVER_TIMEOUT_SEC = 10
 
     def __init__(self, address, node_id):
         self.__receive_buffer = b''
         self.__last_recv_time = None
         self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        self.socket.setblocking(False)
         self.address = (address, self.BASE_PORT + node_id)
 
     async def send(self, data):
-        logger.debug(f'sending {data}')
-        self.socket.sendto(data, self.address)
-        return len(data)
+        logger.debug(f'sending {len(data)} bytes: {data}')
+        return self.socket.sendto(data, self.address)
 
     async def recv(self, bufsize):
-        message = self.socket.recv(bufsize)
-        logger.debug(f'retrieved {message}')
-        return message
+        ready = select.select([self.socket], [], [], self.MAX_SERVER_TIMEOUT_SEC)
+        if ready[0]:
+            data = self.socket.recv(bufsize)
+            logger.debug(f'received {len(data)} bytes: {data}')
+            return data
+        else:
+            raise Exception('simulation UdpStream recv timeout - likely, TCAT is stopped on TCAT Device')

tools/tcat_ble_client/cli/base_commands.py

@@ -181,7 +181,7 @@ class PingCommand(Command):
         data = TLV(TcatTLVType.PING.value, to_send).to_bytes()
         elapsed_time = time()
         response = await bless.send_with_resp(data)
-        elapsed_time = time() - elapsed_time
+        elapsed_time = 1e3 * (time() - elapsed_time)
         if not response:
             return
 
@@ -189,7 +189,7 @@ class PingCommand(Command):
         if tlv_response.value != to_send:
             print("Received malformed response.")
 
-        print(f"Roundtrip time {elapsed_time} s.")
+        print(f"Roundtrip time: {elapsed_time} ms")
 
         return CommandResultTLV(tlv_response)